Interferometric measurement of the biphoton wave function

TL;DR

This paper demonstrates a method to fully characterize the temporal wave function of biphotons by using interference with a reference state, enabling detailed quantum state analysis.

Contribution

It introduces a phase-sensitive interference technique with a coherent reference to reconstruct biphoton wave functions from low-intensity squeezed vacuum states.

Findings

Successfully reconstructed biphoton wave functions.

Demonstrated phase-sensitive interference measurement.

Enabled detailed quantum state analysis.

Abstract

Interference between an unknown two-photon state (a "biphoton") and the two-photon component of a reference state gives a phase-sensitive arrival-time distribution containing full information about the biphoton temporal wave function. Using a coherent state as a reference, we observe this interference and reconstruct the wave function of single-mode biphotons from a low-intensity narrowband squeezed vacuum state.